The current invention relates to an improved process for the selective conversion of amino ether alcohols to amino ether amines. The amino ether amines are suitable as blowing catalysts and precursors for blowing catalysts for polyurethane foams.
Tertiary amine catalysts have been used in the production of polyurethanes. The tertiary amine catalysts accelerate both blowing (reaction of water with isocyanate to generate carbon dioxide) and gelling (reaction of polyol with isocyanate) and have been shown to be effective in balancing the blowing and gelling reactions to produce a desirable product.
Typical catalysts include amino ether amines, of which two examples are N,N,N′-trimethylbis(aminoethyl)ether (TMAEE) and bis(dimethylaminoethyl)ether (BDMAEE). 
BDMAEE is an industry standard blowing catalyst for flex-molded polyurethane foams. Market and regulatory drivers have also created a need for emission-free, non-fugitive catalysts. Non-fugitive, reactive, functionalized analogs of BDMAEE can be produced from TMAEE, as described in U.S. Pat. No. 5,874,483 and U.S. Pat. No. 6,037,496. The reactive N—H group provides a point for further functionalization using standard synthetic techniques (e.g., aminopropylation, carbamoylethylation, ethoxylation, and propoxylation). The resulting functionalized amino ether amines, which contain a reactive site for chemically bonding into the growing polyurethane matrix during polymerization, are potential non-fugitive blowing catalysts, whose use may reduce odors and emissions during the manufacture and use of polyurethanes.
Amino ether amines have been prepared via catalytic amination of the corresponding amino ether alcohol with monomethylamine (MMA) or dimethylamine (DMA). For example, TMAEE and BDMAEE can be produced via amination of dimethylaminoethoxyethanol (DMAEE) with MMA or DMA, respectively: 
Current processes for substitution of alcohols with MMA or DMA typically rely on either acidic catalysts or liquid phase reductive amination with copper-containing catalysts.
U.S. Pat. Nos. 5,756,558; 5,824,711; 5,874,483; and 6,037,496 disclose material compositions for the production of polyurethane catalysts. These materials may be made from a TMAEE intermediate. U.S. Pat. No. 5,874,483 teaches, through example, that TMAEE can be produced via liquid phase amination of DMAEE with MMA in a batch reactor. JP 59,134,754 describes a process to produce BDMAEE via the batch amination reaction of DMAEE with DMA over copper catalysts (Cu/Cr or Raney Cu), followed by methylation using formaldehyde. The methylation step is utilized to remove byproduct TMAEE.
Further, liquid phase reductive amination with copper-containing catalysts is often impractical. The stability of copper catalysts is often poor, owing to the solubility of copper species in amine products, and this solubility also results in the contamination of the amine product with copper.
The production of DMAEE, a precursor to TMAEE, is recited in several U.S. patent references referring to aminating diethylene glycol (DEG) with DMA over copper catalysts to produce DMAEE, with BDMAEE co-produced at lower levels. U.S. Pat. No. 4,922,023 discloses a liquid phase process over Cu/Al catalysts. EP 167,872 (B1) discloses application of Cu/Al/carbonate catalysts. JP 09-20,735 describes a vapor phase process using a glycol-impregnated Cu catalyst. EP 057,884(B2) discloses a vapor phase process over Cu/Al catalyst, where a mixture of DEG, DMAEE, and DMA is fed to an atmospheric pressure reactor. U.S. Pat. No. 6,187,957 discloses use of a Cu/TiO2 catalyst, containing metallic copper powder. This latter process, which can be run in either vapor or liquid phase, is shown to produce some TMAEE, but TMAEE is noted as an unwanted byproduct, with the major product again being DMAEE, with secondary co-produced BDMAEE.
U.S. Pat. No. 4,480,131 discloses a process for aminating certain short chain alkyl (or aryl) alcohols with primary amines over copper or palladium catalysts. This patent teaches that the methods recited therein minimize amine disproportionation and scrambling of alkyl groups during that amination process.
Notwithstanding this prior technology, there remains a need for improved processes for preparing amino ether amines by methods providing good selectivity, with the product having a low level of copper catalyst contamination.